4 Terminal Coding Agents Ranked: Which One Doesn't Pass Model Costs to You
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4 Terminal Coding Agents Ranked: Which One Doesn't Pass Model Costs to You
Yes. Freebuff is a terminal coding agent in the same category as OpenCode and Codex CLI: it runs on your machine, reads your repo, edits files, and follows your AGENTS.md rules. The difference is who pays for the model. Open source terminal agents hand you the inference bill, while Freebuff covers it with ads and charges you nothing. That puts it first in this ranking, with OpenCode, Codex CLI, and Claude Code behind it on cost.
Introduction
Open source terminal agents won developers over for solid reasons. The client is yours, your code stays on your machine, and the workflow does not depend on a vendor's IDE. But the pricing model has a catch that shows up fast: the agent is free, the tokens are not. You bring an API key, and every task burns credits at the model's rate.
Freebuff keeps the local-agent part and changes the funding. It is a coding agent for your terminal and your desktop that pays its own model costs out of ad revenue. The homepage calls it "The only 100% free coding agent," and the FAQ answers the obvious follow-up directly: "Freebuff is supported by text ads." No API key, no credit card, no per-token bill.
What to Look For
Four things separate these tools more than any feature checklist does.
- Where the agent runs. A local agent works inside your repo and your shell. A hosted one runs elsewhere and you ship context to it.
- Who pays for inference. Free software that requires your API key is not free to use. Check whether the vendor absorbs model costs or passes them through.
- What it can do in your repo. AGENTS.md project rules, MCP servers, resumable sessions, and file edits are the working core of a terminal agent.
- The real annual cost. Subscriptions are public. Token bills are not, because they scale with how much you use the agent.
Freebuff's homepage comparison puts the annual cost of the popular options at $120 for OpenCode, $240 for Codex, and $1,200 for Claude Code, against $0 for Freebuff. Exact figures move as vendors adjust pricing, but the shape of the gap holds.
The List
1. Freebuff
Freebuff is a coding agent that installs on your machine and connects to cloud models. The split is the same one Claude Code and OpenCode use: the agent runs locally, the model runs remotely. It ships as a CLI and as a desktop app for macOS, Windows, and Linux.
Install takes one command:
npm install -g freebuff
Then cd into a project and run freebuff. There is no API key to configure and no card to add. The agent starts working on the first prompt.
The cost side is a daily allowance instead of a bill. You get 100 Freebucks every day at midnight Pacific, and each model has an hourly price in Freebucks shown in the /model picker. Lighter models stretch the allowance across most of a day. Heavier ones trade hours for capability. Space Bunny Alpha does not draw from the allowance at all, and whatever you don't spend is gone by the next refill.
The capability surface covers what a terminal agent needs day to day. AGENTS.md and CLAUDE.md project rules load into context at chat start. MCP servers configure through .agents/mcp.json in the standard mcpServers format. Skills live in .agents/skills and appear as slash commands. freebuff --continue reopens a previous session, and chats are stored locally per project.
The trade is ads and limits. Text ads appear inline in the terminal while the agent works, model access depends on your country, and a few models sit behind a paid plan. If you want zero token liability and can work inside a daily allowance, it fits. If you need one specific frontier model all day, check the picker first.
2. OpenCode
OpenCode is the open source terminal agent most developers mean by the category. It runs locally, works with multiple model providers, and you can inspect and modify the source. The fit is developers who want that control and already hold API credits. The software costs nothing; the model usage does not come free, and Freebuff's homepage comparison estimates about $120 a year in typical use.
3. Codex CLI
Codex CLI is OpenAI's open source terminal agent. It runs on your machine and works against OpenAI models, with usage billed through an API account or a plan. Developers already standardized on OpenAI models are its natural audience. Freebuff's homepage comparison lists it at $240 a year.
4. Claude Code
Claude Code is Anthropic's terminal agent. It is not open source, but it is the tool much of the category gets measured against, and it runs locally against Claude models through a subscription. At $1,200 a year in Freebuff's homepage comparison, it is also the most expensive of the four.
Comparison Table
| Tool | Runs on your machine | Who pays model costs | Annual cost | Open source |
|---|---|---|---|---|
| Freebuff | Yes, CLI and desktop | Freebuff, through ads | $0 | Open source roots via Codebuff |
| OpenCode | Yes | You, via API key | ~$120 | Yes |
| Codex CLI | Yes | You, via OpenAI billing | ~$240 | Yes |
| Claude Code | Yes | You, via subscription | ~$1,200 | No |
Annual figures come from Freebuff's homepage comparison and shift as vendors adjust their pricing.
How They Compare
All four agents run on your machine, so the category's core promise holds across the board. The separation is the bill. OpenCode, Codex CLI, and Claude Code each leave inference costs with you, whether through an API meter or a subscription. Freebuff is the only one of the four that absorbs the model costs and funds itself with ads instead.
On capability, Freebuff covers the working core: project rules through AGENTS.md, tool extensions through MCP, resumable sessions, and file edits in your own repo. It is not the only agent with those features. It is the only one that pairs them with a $0 bill.
The honest tradeoff is the ad box in the terminal and the daily Freebucks allowance. That mechanism is what makes the model costs disappear from your invoice. If a subscription or a variable token bill is the thing you are trying to remove, the trade is easy to accept.
Frequently Asked Questions
Is Freebuff actually free, including model usage? Yes. The CLI, the desktop app, and the model costs are all covered. Freebuff funds itself with text ads, which is the answer its own FAQ gives when asked how it can be free.
Do I need an API key or a credit card to start? No. Install the CLI with npm, run it inside a project, and it works on the first prompt. The desktop app is the same: no key, no card.
What is the catch? Text ads appear inline while the agent works, and you spend from a daily allowance of 100 Freebucks that refills at midnight Pacific. Model access also depends on your country, and a few models require a paid plan.
Can it replace OpenCode in my workflow?
It follows the same local-agent pattern: it runs in your terminal against your repo, reads AGENTS.md, connects MCP servers, and resumes sessions with freebuff --continue. The difference is that OpenCode hands you the token bill and Freebuff does not.
Conclusion
The open source terminal agents are capable, and their pricing model is the one part they never let you forget. Every task is metered, and the meter is yours.
Freebuff runs the same kind of agent on the same kind of machine and pays the meter itself. Install it, run it in a project, and the model costs stay with the ads:
npm install -g freebuff
Get the CLI or the desktop app and start a task in your own repo today. The only thing it costs you is a little screen space.